Fuse-plug



A. J. ZARLINGA AND E. J. KORBEL.

FUSE PLUG. APPLICATION FILED MAY 27. 1918.

1 222,079. Patented Nov. 18, 1919.

Wri /v e55 UNITED STATES PATENT OFFICE.

ANGELO J. ZARLINGA AND EDWARD JOSEPH KORBEL, OF CHICAGO, ILLINOIS.

FUSE-PLUG.

Specification of Letters Patent.

Application filed May 27, 1918. Serial No. 236,787.

To all whom it may con'cern:

Be it known that we, ANGELO J. ZARLINGA and EDWARD J. Korean, citizens of the United Statesof America, and residents of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Fuse-Plugs, of which the following is a specification.

This invention relates to inclosed electric fuses of the plug type such as are used in electric lighting circuits.

The main objects of this invention are to provide an improved fuse plug in which the fuses can -be readily replaced; to provide improved indicating means for showing whether or not the fuse has been blown, without the necessity of first removing the plug from its socket; and to provide an improved fuse plug of simple construction which is inexpensive to manufacture.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which Figure 1 is a longitudinal section of the fuse plug showing the indicating means in its normal position.

Fig. 2 is a plan of one of the contact members as it appears before it is bent into final form.-

Fig. 3 is an enlarged sectional view of the same as it appears in Fig. 1. i

Fig. 4 is a sectional view of the plug taken on the line 4:4.- of Fig. 1.

' The hereindescribed fuse plug is designed so that the indicating means will be operated 'by the expanding gases produced by the burning of the fuse wire, said indicating means being so arranged as to be forced to protrude beyond the casing of the plug where it can be readily and easily seen or felt in determining the condition of the fuse.

In the construction shown in the drawings, the improved form of fuse plug comprises a hollow cylindrical casing 1 secured to an insulatin member 2 by means of a threaded metal ic ferrule 3 and having a plunger. 4 slidably mounted therein and adapted to protrude through the open end thereof The casing 1 is made of suitable'insulating material, being bored through the center thereof so as to provide a chamber 5 extending throughout the length of said casing. One end of the casing is threaded to fit the copper ferrule 3 which in turn fits the standard fuse plug socket, said ferrule being provided with an inwardly projecting flange 6 at one end thereof for securing the member 2. The inner surface 7 of the casing 1 is provided with a shoulder 8 near its upper end to limit the outward movement of the plunger 4. The casing is countersunk at its forward end so as to provide a conical seat 9 for limiting the inward movement of the plunger, and the lower end of the, casing l is counterbored to provide a seat 10.1 for the insulating member 2.

The insulating member 2 is in the form of a disk 10 having a tubular stem 11 extending into the chamber 5, said disk and stem being used to support and insulate the binding post 12. The stem 11 has a greater diameter at its base so as to provide an enlarged portlon which is longitudinally grooved at 13.

The binding post 12 is connected electricallythrough the tubular stem 11 with a contact 'cap 14c projecting beyond the disk 10 and is provided near its upper end with an aperture 15 for receiving one end of a fuse wire 16 where it is secured by a screw 17. After the binding post and stem 11 have been assembled, the lower end of the binding post is peened or soldered so as to secure the contact bur- 1 f thereto, said bur being countersunk so that the contact face thereof will be flush with the peened end of the post 12. I

A contact member 18 for electrically connecting the fuse wire ,16 with the ferrule 3 consists of a piece of sheet metal of the'form shown in Fig. 2. The washer-like body portlon of member 18 encircles the stem 11, the

tongues'19 are bent around the edges of disk 10, and the spring tongue 20 is seated in the groove 13 of the insulating member 2.

A collar 21 is provided for holding the lower end of the fuse into electrical contact with the spring 20 so aS to efiect the connection between the contact cap 14 and the ferrule The collar 21 is made preferably of insulating material and has sliding engagementwith the projecting part 11 of the insulating member 2. When it is desired to place a new fuse wire into the plug the ferrule 3 is unscrewed from the casing 1- so as to permit the removal of said casing from the disk 10. The insertion of the fuse may then be readily accomplished by fastening one end thereof to the binding post by means of the screw. 17 and then slidin the collar 2'1'down over the fuse wire and binding post until the free end of the fuse wire is forced into contact with the spring 20.

The plunger 4 is in the form ofa tube internally threaded at one end to receive aplug 22! shaped to coact With the bearingsurface 9 of the casing 1 for limiting the inward movement of the plunger and to pro vide a dust-tight closure for the casing. A

flange or shoulder 23 at the other end of the plunger coacts with the shoulder 8- of the tact member adjacent said means, and a col-; lar slidable on said means for frictionally clamping the fuse element against said contact member.

2. In a fuse plug, a stem, a bindingpost carried thereby, a fuse element having one end connected to said binding post, a contact member at the lower end of said stem and insulated from said binding post, and a collar slidably mounted on said stem and adapted to force the free end of said fuse element into electrical contact with said contact member.

3. An electrical fuse plug, comprising a casing, a fuse element arranged Within said casing, a plunger slidably mounted within said casing and adapted to be forced outward by the expansion of gases produced by the fusing of said fuse element, and coacting shoulders on said casing and plunger for limitin the outward movement of said plunger, sald plunger comprisin a tube and a plug therefor having threa ed engagement with the outer end thereof, said plu being shaped to coact with the walls of sai casing for limiting the inward movement of said plunger and to provide a tight closure for said casing.

4. An electrical fuse plug comprising a casing, a threaded ferrule on said casing, an insulating member mounted within said casing and secured thereto by means ofsaid ferrule, a binding post carried by said insulating member and extending Within said casing, a contact member mounted on said insulating member and having electrical contact with said ferrule, a fuse element within said casing and having one end thereof secured to said binding post, and a collar slidably mounted on said insulating member and adapted to force the free end of said fuse element into electrical contact with said contact member.

5. A fuse plug comprising a casing, a stem Within said casing, a fuse supported by said stem, and a plunger slidably mounted within said casing and adapted to be forced outward by the expansion. of gases produced by the burnin of said fuse, said plunger comprising a tube surrounding said stem and fuse and a plug having threaded engagement with said tube so as to close the outer end thereof, said plug being shaped to coact with the walls of said casing for limiting the inward movement of said plunger and to provide a dust-tight closure at the forward end of said casing.

Signed at Chicago this 23rd day of May, 

